Daryl, that steel "lever" you mention is known as a sprue cutter. The hole in it would be centered over the open end of the mold, and molten lead bullet alloy is poured in. After it sets up, a mallet is used to tap the sprue cutter laterally, thus cutting off the sprue and any extra alloy on top. The tapered hole in the sprue cutter acts as a small funnel for the molten alloy, and the sharp lower edge facilitates cutting off the sprue. The cut off bit is dumped back into the melting pot.
Evidence of this sprue cutting process can be seen on most cast bullets, and on cast lead round balls. It is most often seen on the base, but this is a nose-pour type mold, so the sprue cutter is on the nose end. I kinda figured that the hole in the female face of the mold top was for the screw attaching the sprue cutter to the mold top. The maker could have drilled a blind hole, but chose to drill all the way through.
craigd, your idea of this being built to get an obsolete gun shooting again seems plausible, as does the idea that thicker walled brass tubing could have been grafted to suitable donor case heads. Some would say that's more trouble than it's worth, but certainly no worse than cobbling up shells to get an old pinfire gun shooting again. Most bullet alloy shrinks slightly as it cools, so if the inside was well polished, it probably didn't stick bullets, even without taper. Paul Matthews shows a remotely similar nose pour mold for a paper patch bullet in his book, "The Paper Jacket". The large flat nose would also provide a spot to give a little push with a dowel too. One way to know would be for Daryl to enlist a friend who does bullet casting to fire up the pot and try pouring a few.
